Propylene glycol solutions

Fig. 1. Solubility of vanillin in (a) ethanol solutions, (b) propylene glycol solutions, and (c) glycerol solutions, where A is 40°C B, 30°C C, 20°C D, 10°C ...

Acute Toxicity. The LD50 following oral administration of parathion, either in propylene glycol solutions or in aqueous suspensions of the 15% wettable powder, has been determined for rats, mice, and guinea pigs. The lethal dose was approximated for rabbits and dogs. The results of these experiments are summarized in Table I. Statistical evaluation was by the method of Wilcoxon and Litchfield (11). 

As the concentration of parathion in the propylene glycol solutions is increased, it follows that the area covered by the solution is decreased. That this is a factor in toxicity is indicated by the greater toxicity of the 10 mg. per ml. solution than the 50 mg. per ml. solution. This relationship appears to be true also of the various dry preparations, in that the 1% powder is somewhat more toxic than the 15%. The addition of water to convert the powder to paste does not appreciably influence the toxicity. In comparable concentrations the wettable powder formulation is less toxic than the propylene glycol solution. 

Naphthyl 2-fluoroethyl ether was readily prepared by warming an alkaline solution of 2-naphthol with 2 2 -difluorodiethyl sulphate. Subcutaneous injection into mice of the propylene glycol solution showed that the compound had a l.d. 50 of approximately 60 mg./kg. and was therefore much less toxic than M.F.A. 

From a study of the fluoroacetates so far mentioned, it appears that any compound which can give rise to fluoroacetic acid (or the fluoroacetate ion), either by hydrolysis or by oxidation (or both), is toxic. The toxic grouping is thus F-CH2-CO, and any substitution in this radical destroys the toxicity as far as relatively simple compounds are concerned. We had reached this conclusion by May 1943.1 We subsequently showed that esters of / -fluoropropionic acid were non-toxic, whereas esters of y-fluorobutyric acid were shown by American workers to be toxic. In 19442 we reported the synthesis of ethyl 5-fluoro-pentanecarboxylate, F,[CH2]g C02Et (I). This is a stable, colourless liquid and we showed that it possessed very potent toxic properties of the fluoroacetate type. By subcutaneous injection of the propylene glycol solution into mice the l.d. 50 was 4 mg./kg. Methyl fluoroacetate (II) may be taken as a convenient standard (p. 115) and has a l.d. 50 of about 6 mg./kg. for saline solutions, and 15 mg./kg. for propylene glycol solution.3 Therefore ethyl 5-fluoropentanecarboxylate was about 7 times as toxic as methyl fluoroacetate (molecule for molecule).4... 

Welgaod and Mershon22 tested 39 subjects for skin reactions to CR, using 1-cm2 patches soaked with CR-propylene glycol solutions. Each patch was wetted with 0.1 ml of 0.01, 0.05, 0.10, 0.25, 0.50, or 1.0X CR, Ezposure times were 5 and 30 min, and tests were made at 18.3 and 25.6°C. The concentration of CR did not affect the time of onset of sensation higher temperature decreased onset times. Subjects differed widely, both In time of onset and termination of Irritation and In reported Intensity of sensation. Intensity was not related to concentration of CR, ezposure time, or temperature. The degree of erythema was variable, but It disappeared In 2-4 h. All CR concentrations were judged to be relatively harmless. 

In concentrations greater than 10%, propylene glycol may act as an irritant in some patients those with eczematous dermatitis may be more sensitive. Allergic contact dermatitis occurs with propylene glycol, and a 4% aqueous propylene glycol solution is recommended for the purpose of patch testing. 

Ong, J. T., and E. Manoukian. 1988. Micellar solubilization oftimobesome acetate in aqueous and aqueous propylene glycol solutions of nonionic surfactarffifearm. Res. 5 704-708. 

Add the bromide and sodium metabisulfite to about 50.0 to 75.0ml of hot distilled water at about 125F/51C. Stir until completely dissolved, and then add this solution to the propylene glycol solution. 

Friedheim EAH (1952) Propylene glycol solution of arsenic medicaments. US Patent 3,593,434... 

B Combinations that were not investigated are indicated by dashes b Water-propylene glycol solutions c Aqueous sodium dodecyl sulfonate solutions d Complexing only after heating... 

Poly-VCy can form a stable complex with polyguanylic add (poly G) and polyinosic acid (poly I) in water-propylene glycol solution. However, die structure of the complex appears to be irregular14. Poly-9-vinylhypoxanthine tends to produce the complex to a lesser extent as compared with the other vinyl polymers, probably due to its low solubility10. ... 

Solubility practically insoluble in water, glycerin, propylene glycol, solutions of alkali hydroxides, and dilute aqueous mineral acids. Freely soluble in acetone, benzene, ethanol (95%), ether, methanol, toluene, fixed oils, and mineral oil. More soluble than butylated hydroxyanisole in food oils and fats. 

Formulation of a tablet coating solution 20% docusate sodium 2-15% sodium benzoate 0.5% propylene glycol solution made in ethanol (70%). 

Viscosity of calcium chloride and sodium chloride solutions is compared with ethylene and propylene glycol solutions in Fig. 2. It is apparent that there is a major difference in the viscosity of these fluids at low temperatures, which is very important for equipment design. 

Propylene glycol (1000 g) and methylparaben (15 g) are mixed together until all solids are dissolved. Hydroxypropyl methylcellulose 4000 CPS (CPS refers to centipoise, a designation of viscosity 30 g) is added to and dispersed in the propylene glycol solution, and this resulting mixture is then added to an aqueous solution of disodium edetate (5.0 g) and sodium lauryl... 

Ethyl 9 fluorononanecarboxylate (VII) was found to be even more toxic than ethyl 5 fluoropentanecarboxylate by injection into rabbits, the l.d. 50 for a propylene glycol solution of (VII) being 0-2 mg./kg. Mice and rats were sbghtly more resistant, but exhibited convulsions of the general fluoroacetate type. On account of the high boiling-point of the material, no inhalation experiments were attempted. 2 Fluoroethyl 9 fluorononanecarboxylate (VIII) was found to be no more toxic than the corresponding ethyl ester by injection into mice. Each had a l.d. 50 of about 10 mg./kg. This anomaly is discussed later. 

Synthesis of poly(aspartic add) from maleic acid derivatives and from aspartic acid under microwave irradiation conditions has been described by Pielichowski et al. (Scheme 14.33) [69, 70]. The reactions were performed in propylene glycol solutions in the temperature range 160 to 230 °C in a multimode microwave reactor. Poly(aspartic acid) with number-average molecular weights of 6150 to 18 500 g mol was obtained in good yield (50 to 85%). 

Table 7.20 Bolling Points of Aqueous Propylene Glycol Solutions (iq)...

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